Service manual

15-3
CONTROL SYSTEM > GC 24
SM HADDCI 1-A.2 GB
15.2.8 Temperature Sensors
CTT  - Compressor Top Temperature
OAT  - Outdoor Air Temperature
OMT  - Outdoor Middle Temperature
OCT  - Outdoor Coil (heat exchanger) Temperature
HST  - Heat Sink Temperature
15.2.9 Base Heater
Heating element designed to melt any ice that is accumulated on the outdoor unit base during low heating
operation.
15.3 General Operating Rules
15.3.1 Initialization
Initialization process is the first operation done each time power is up. The targets of the initialization are:
● Addressing of IDU’s
● Identification of connected IDU’s
● IDU Matching Check
● EEV’s homing (reset position)
● Restoring Parameters from EEPROM/Jumpers/Dipswitches
15.3.1.1 IDU’s Initialization Faults Definition and System Response
Fault Activity Fault Display System response

Missing IDU
Update new IDU status stored at
the EEPROM.
System configuration
Changed

Change in IDU
Family/Capacity
Group
Fault will be stored in EEPROM
as an inactive failure of the
specific IDU
System configuration
Changed

IDU Code Exceed
Limit
Fault will be stored in EEPROM
for the specific IDU
System Configuration
Problem
System will switch
to SB

Total IDU Code
Exceed Limit
ODU fault will be stored in
EEPROM
System Configuration
Problem
System will switch
to SB
15.3.1.2 WNG72/80 Definition
Indoor Model Family Model IDU Code
WNG72 WNG 18 C 3
WNG80 WNG 30 A 3
The models are named by their family and capacity. For example WNG 9 means a wall mounted units with a
nominal cooling capacity of 9000 Btu/hr (which is equivalent to 2.5 kW). The nominal capacity of the indoor
unit sets it’s capacity code
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